The update for Android 4.1 Jelly Bean is out for models i9023, i9020T and i9020A are out for the models that work with T-Mobile The update for the Nexus S 4G for the Sprint network is not out, yet.

"We've started rolling out Android 4.1, JellyBean, to Nexus S phones on a number of carriers with more to come. Enjoy," Google posted to the Google+ Nexus account.

Before updating any smartphone is always a good idea to backup all of your data. We also recommend that you read what the update does, it sometimes changes the homescreens and settings such as taking a screenshot which can be confusing. Sometimes updates ad glitches while fixing others.

The updates are also cutting out some features due to the massive amount of patent infringement lawsuits between all the smart phone makers. The unified search feature is removed in these updates.

Jelly Bean features improved performance throughout the system, including faster orientation changes, faster responses when switching between recent apps, and smoother and more consistent rendering across the system through vsync and triple buffering.

Better Keyboard - Android’s dictionaries are now more accurate, more relevant. The language model in Jelly Bean adapts over time, and the keyboard even guesses what the next word will be before you’ve started typing it.

Jelly Bean has more reactive and uniform touch responses, and makes your device even more responsive by boosting your device’s CPU instantly when you touch the screen, and turns it down when you don’t need it to improve battery life.

Accessibility features include gesture mode for blind users, text traversal, talkback and support for braille services.

And T-Mobile never sold the Nexus S either. The GSM Nexus S was only available for purchase online or through best-buy. Actually none of the Nexus GSM versions (one, S, Galaxy) have ever been sold through carriers.